Dampp Chaser

This is a product I cannot recommend highly enough. In 1999 I installed 15 of them in Steinways in the Guildhall School of Music & Drama which dramatically reduced my tuning and maintenance schedule for those instruments. I was the UK National Technical support agent for several years.

These are the details from the company website which I cannot improve upon

"The Piano Life Saver is a piano humidity control system. It keeps your piano on pitch and prevents damage from climate and environmental effects, giving you professional performance level tonal quality and keyboard control.

Piano technicians and major piano manufacturers recommend installing the Piano Life Saver System to protect your piano’s internal parts, improve keyboard control, and maintain tuning stability. The System keeps piano humidity levels consistent by activating the Dehumidifier during highly humid conditions, and when the environment gets too dry, the Humidifier replaces moisture inside the piano.

The System is truly a lifesaver for piano maintenance, tuning, and combating dry or humid conditions that cause costly damage to your piano. Protect your investment by having our piano climate control system installed out of sight, inside your piano. Professional installation is required for warranty coverage"